Pear
2008/9 Schools Wikipedia Selection. Related subjects: Plants
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 European Pear branch with fruit
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About 30 species; see text |
A pear is a tree of the genus Pyrus and the juicy fruit of that tree, edible in some species. The English word pear is probably from Common West Germanic *pera, probably a loanword of Vulgar Latin pira, the plural of pirum, which is itself of unknown origin. See also Peorð. The place name Perry can indicate the historical presence of pear trees. The term "pyriform" is sometimes used to describe something which is "pear-shaped".
The pear is classified within Maloideae, a subfamily within Rosaceae. The apple (Malus ×domestica) which it resembles in floral structure, is also a member of this subfamily. In both cases the so-called fruit is composed of the receptacle or upper end of the flower-stalk (the so-called calyx tube) greatly dilated, and enclosing within its cellular flesh the five cartilaginous carpels which constitute the "core" and are really the true fruit. From the upper rim of the receptacle are given off the five sepals, the five petals, and the very numerous stamens. Another major relative of the pear (and thus the apple) is the quince.
The form of the pear and of the apple respectively, although usually characteristic enough, is not by itself sufficient to distinguish them, for there are pears which cannot by form alone be distinguished from apples, and apples which cannot by superficial appearance be recognized from pears. A major distinction is the occurrence in the tissue of the fruit, or beneath the rind, of clusters of lignified cells known as "grit" in the case of the pear, while in the apple no such formation of woody cells takes place. The appearance of the tree—the bark, the foliage, the type of inflorescence (i.e. form of the flower cluster)—is, however, usually quite characteristic in the two species.
The genus is thought to have originated in present-day western China in the foothills of the Tian Shan Mountains, and to have spread to the east and west along mountain chains, evolving into a diverse group of over 20 widely recognized primary species. The cultivated European pear (Pyrus communis), whose number is enormous, are without doubt derived from one or two wild species (P. pyraster and P. caucasica), widely distributed throughout Europe, and sometimes forming part of the natural vegetation of the forests. In England, where the pear is sometimes considered wild, there is always the doubt that it may not really be so, but the produce of some seed of a cultivated tree deposited by birds or otherwise, which has degenerated into wild spine-bearing trees. Asian species with medium to large edible fruit include P. pyrifolia, P. ussuriensis, P. ×bretschneideri, P. ×sinkiangensis, and P. pashia. Other small-fruited species are frequently used as rootstocks for the cultivated species.
The cultivation of the pear extends to the remotest antiquity. Traces of it have been found in the Swiss lake-dwellings; it is mentioned in the oldest Greek writings, and was cultivated by the Romans. The word "pear" or its equivalent occurs in all the Celtic languages, while in Slavonic and other dialects different appellations, but still referring to the same thing, are found—a diversity and multiplicity of nomenclature which led Alphonse de Candolle to infer a very ancient cultivation of the tree from the shores of the Caspian to those of the Atlantic. A certain race of pears, with white down on the under surface of their leaves, is supposed to have originated from P. nivalis, and their fruit is chiefly used in France in the manufacture of Perry (see Cider). Other small-fruited pears, distinguished by their precocity and apple-like fruit, may be referred to P. cordata, a species found wild in western France, and in Devonshire and Cornwall. Pears have been cultivated in China for approximately 3000 years.
Botany
Pears are native to coastal and mildly temperate regions of the Old World, from western Europe and north Africa east right across Asia. They are medium sized trees, reaching 10–17 m tall, often with a tall, narrow crown; a few species are shrubby. The leaves are alternately arranged, simple, 2–12 cm long, glossy green on some species, densely silvery-hairy in some others; leaf shape varies from broad oval to narrow lanceolate. Most pears are deciduous, but one or two species in southeast Asia are evergreen. Most are cold-hardy, withstanding temperatures between −25 °C and −40 °C in winter, except for the evergreen species, which only tolerate temperatures down to about −15 °C.
The flowers are white, rarely tinted yellow or pink, 2–4 cm diameter, and have five petals. Like that of the related apple, the pear fruit is a pome, in most wild species 1–4 cm diameter, but in some cultivated forms up to 18 cm long and 8 cm broad; the shape varies in most species from oblate or globose, to the classic pyriform ' pear-shape' of the European Pear with an elongated basal portion and a bulbous end.
The pear is very similar to the apple in cultivation, propagation and pollination.
There are about 30 primary species, major subspecies, and naturally occurring interspecific hybrid of pears.
Major recognized taxa
Cultivation
The pear may be readily raised by sowing the pips of ordinary cultivated or of wilding kinds, these forming what are known as free or pear stocks, on which the choicer varieties are grafted for increase. For new varieties the flowers should be fertilized with a view to combine, in the seedlings which result from the union, the desirable qualities of the parents. GraftingThe dwarf and pyramid trees of the European pear, more usually planted in gardens, are obtained by grafting on the quince stock, the Quince A, C, or Provence quince being the best; but these rootstocks, from their surface-rooting habit, are most suitable for soils of a cold damp nature. These trees will be 50 to 70 percent of the size of trees on common pear roostock, will bear fruit earlier, increase yield, and, in some cases, increase fruit size. Some of the finer pears do not unite readily with the quince, and in this case double working is resorted to; that is to say, a graft-compatible pear, usually 'Old Home' or 'Buerre Hardy' is first grafted on the quince, and then the choicer pear is grafted on the pear introduced as its foster parent. Several cultivars, including the prized 'Doyenne du Comice', are compatible directly on quince. Common pear rootstock (P. communis), having an inclination to send its roots down deeper into the soil, is the best for light dry soils, as the plants are not then so likely to suffer in dry seasons. Seedling rootstocks have been replaced with clonally propagated rootstocks, including the 'Old Home' × 'Farmingdale' series, 'Pyriam', and others. While generally not as dwarfing as quince, some of these rootstocks will reduce tree size to 60 to 80 percent of a standard tree on seedling rootstock. Planting Young TreesIn selecting young pear trees for walls or espaliers, some persons prefer plants one year old from the graft, but trees two or three years trained are equally good. The trees should be planted immediately before or after the fall of the leaf. The wall trees require to be planted from 25 to 30 ft. apart when on free stocks, and from 15 to 20 ft. when dwarfed. Where the trees are trained as pyramids or columns they may stand 8 or 10 ft. apart, but standards in orchards should be allowed at least 30 ft., and dwarf bush trees half that distance. In the formation of the trees the same plan may be adopted as in the case of the apple. For the pear orchard a warm situation is very desirable, with a soil deep, substantial, and thoroughly drained. Any good free loam is suitable, but a calcareous loam is the best. Pear trees worked on the quince should have the stock covered up to its junction with the graft. This is effected by raising up a small mound of rich compost around it, a contrivance which induces the graft to emit roots into the surface soil. Training and PruningThe fruit of the pear is produced on spurs, which appear on shoots more than one year old. The mode most commonly adopted of training wall pear-trees is the horizontal. For the slender twiggy sorts the fan form is to be preferred, while for strong growers the half-fan or the horizontal is more suitable. In the latter form old trees, the summer pruning of which has been neglected, are apt to acquire an undue projection from the wall and become scraggy, to avoid which a portion of the old spurs should be cut out annually. The summer pruning of established wall or espalier-rail trees consists chiefly in the timely displacing, shortening back, or rubbing off of the superfluous shoots, so that the winter pruning, in horizontal training, is little more than adjusting the leading shoots and thinning out the spurs, which should be kept close to the wall and allowed to retain but two or at most three buds. In fan-training the subordinate branches must be regulated, the spurs thinned out, and the young laterals finally established in their places. When horizontal trees have fallen into disorder, the branches may be cut back to within 9 in. of the vertical stem and branch, and trained in afresh, or they may be grafted with other sorts, if a variety of kinds is wanted.  HarvestSummer and autumn pears should be gathered before they are fully ripe, while they are still green, but snap off when lifted. If left to ripen and turn yellow on the tree, the sugars will turn to starch crystals and the pear will have gritty texture inside. The 'Jargonelle' should be allowed to remain on the tree and be pulled daily as wanted, the fruit from standard trees thus succeeding the produce of the wall trees. In the case of the 'Passe Crassane', long the favored winter pear in France, the crop should be gathered at three different times, the first a fortnight or more before it is ripe, the second a week or ten days after that, and the third when fully ripe. The first gathering will come into eating latest, and thus the season of the fruit may be considerably prolonged. It is evident that the same method may be followed with other sorts which continue only a short time in a mature state. Diseases and pestsUses  Three species account for the vast majority of edible fruit production, the European Pear Pyrus communis cultivated mainly in Europe and North America, the Chinese white pear (bai li) Pyrus ×bretschneideri, and the Nashi Pear Pyrus pyrifolia (also known as Asian Pear or Apple Pear), both grown mainly in eastern Asia. There are thousands of cultivars of these three species. A species grown in western China, P. sinkiangensis, and P. pashia, grown in southern China and south Asia, are also produced to a lesser degree. Other species are used as rootstocks for European and Asian pears and as ornamental trees. The Siberian Pear, Pyrus ussuriensis (which produces unpalatable fruit) has been crossed with Pyrus communis to breed hardier pear cultivars. The Bradford Pear (Pyrus calleryana 'Bradford') in particular has become widespread in North America and is used only as an ornamental tree. The Willow-leafed Pear (Pyrus salicifolia) is grown for its attractive slender, densely silvery-hairy leaves. Pears are consumed fresh, canned, as juice, and dried. The juice can also be used in jellies and jams, usually in combination with other fruits or berries. Fermented pear juice is called perry. Pears will ripen faster if placed next to bananas in a fruit bowl. They stay fresh for longer if kept in a fridge. Pears are the least allergenic of all fruits. Along with lamb and soya formula, pears form part of the strictest exclusion diet for allergy sufferers. Pear wood is one of the preferred materials in the manufacture of high-quality woodwind instruments and furniture. It is also used for wood carving, and as a firewood to produce aromatic smoke for smoking meat or tobacco. |
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